In the drilling of oil and gas wells, a drill bit is used to dig thousands of feet into the crust of the earth. Oilrigs typically employ a derrick that extends above the well drilling platform and that can support joints of drill pipe connected end to end during the drilling operation. As the drill bit is pushed into the earth, additional pipe joints are added to the "string" of drill pipes. The drill string pipes each have an internal, longitudinally extending bore for carrying fluid drilling mud from the well drilling platform to a drill bit supported at the lower or distal end of the drill string.
Drilling mud lubricates the drill bit and carries away well cuttings generated by the drill bit. The cuttings are carried in a return flow stream of drilling mud through the well annulus and back to the well drilling platform at the earth surface. When the drilling mud reaches the surface, it is contaminated with small pieces of shale and rock known as well cuttings or drill cuttings.
In the past, well cuttings have been separated from the reusable drilling mud with commercially available separators that are known as "shale shakers." Some shale shakers are designed to filter coarse material from the drilling mud while other shale shakers are designed to remove finer particles from the well drilling mud. After separating well cuttings, the drilling mud is returned to a mud pit where it can be supplemented and/or treated prior to transmission back into the well bore via the drill string to repeat the process.
The disposal of the separated shale and cuttings is a complex environmental problem. Drill cuttings contain not only the mud product, which would contaminate the surrounding environment, but also can contain environmentally hazardous oil, especially when drilling in a marine environment.
In the Gulf of Mexico for example, there are hundreds of drilling platforms that drill for oil and gas by drilling into the sea floor. These drilling platforms can be in many hundreds of feet of water. In such a marine environment, the water is typically crystal clear and filled with marine life that cannot tolerate the disposal of drill cuttings waste containing a combination of shale, drilling mud, and oil. Therefore, there is a need for a simple, yet workable solution to the problem of disposing of oil and gas well cuttings in offshore marine and other fragile environments. Traditional methods of cuttings disposal have been dumping, bucket transport, cumbersome conveyor belts, and washing techniques that require large amounts of water. Adding water creates additional problems of added volume and transport problems. Installing conveyors requires major modification to the rig area and involves many installation hours and very high cost.